Recently, modern medical techniques which are relatively non-invasive have been developed for viewing and performing different medical procedures on the interior structure of body parts. Medical instruments for performing these procedures are known generally as endoscopes and specifically include arthroscopes, spinalscopes, laproscopes, esophagoscopes and others. These instruments typically include a scope which is inserted into the body part to be examined. With an arthroscope, for example, the scope is coupled to a camera assembly and the camera assembly, in turn, is connected to a video display for generating a picture of the interior structure of the joint. Consequently, the operator of the arthroscope is able to view, in real-time, the interior structure of the body as the scope is inserted into the body. By viewing the internal body structure, a diagnosis can be made and appropriate treatment prescribed.
For illuminating the interior body structure, an endoscope assembly includes optical illumination fibers that terminate at the distal or viewing end of the scope and direct light into the body. The optical illumination fibers in turn, are coupled to a high intensity light source, or "light box" that includes a light bulb (i.e. xenon or metal halide). Such a light box, because of its size, power and control requirements is typically mounted externally to the probe and remotely from hand-held components of the endoscope. With an arthroscope, for instance, the scope portion of the endoscope and a portion of the camera assembly are mounted in a hand held housing, and the light box is external to this housing in a separate console. Such an arrangement necessitates a flexible light transmissive conduit which connects the external light box to the illumination fibers within the endoscope assembly. These types of light transmissive conduits must be precisely connected to the scope assembly and to the external light box. This requires precision design and construction of the endoscope assembly.
Existing light boxes have a number of drawbacks. First, the light boxes often have complicated connector assemblies which are necessary to connect the light box to the fiber optic illumination cable. One such connector is disclosed in U.S. Pat. No. 4,253,448 issued to Terada for an invention entitled "Endoscope Connector". The Terada connector fixably attaches the fiber optic cable to the light box and does not permit disconnection of the fiber optic cable from the light box.
Another plug and socket type connector is disclosed in U.S. Pat. No. 4,867,138 issued to Kubota et al. for an invention entitled "Rigid Electronic Endoscope". This connector while allowing the fiber optic cable to be disconnected from the light box, does not allow rotation of the cable relative to the light box. Further, accidental disconnection is possible because the plug is retained frictionally in its socket.
Yet another commonly used device for connecting an optic cable to a light box is a typical screw-in connector. A screw-in connector, however, does not permit quick connections and disconnections and does not allow rotation of the fiber optic cable relative to the light box once installed. Another commonly used connector is a single bearing retainer connector. This connector uses a single bearing in the socket to engage a groove in the plug to retain the plug in engagement with the socket. Consequently, the non-symmetrical force resulting from the single bearing often results in improper alignment between the light box and the cable.
Fiber optic light sources provide the required intensity of light by operating at high power levels. As a result, these high power levels reduce the life expectancy of the bulbs producing the light, which in turn necessitates periodic replacement of the bulbs. To prevent bulb failures during a surgical procedure, it is often desirable to replace the light bulb of a light box before it actually ceases providing light. In fact, many bulb manufacturers provide a maximum bulb use period and recommend replacing bulbs used longer than the maximum use period.
For this reason, some light boxes include an hour meter which allows the operator to monitor the operating time of the light box. For some light boxes, the resetting the hour meter when changing a bulb is complicated because the light box must be partially disassembled to reset the timer. Disassembly by untrained individuals can result in an electrical shock to the person and damage to the light box components. For these reasons, some manufacturers suggest sending the entire light box to the manufacturer. To avoid sending the light box to the manufacturer, many hour meters are never reset. Instead, the operator must note the meter reading at the time of bulb replacement and calculate the meter reading for the next bulb replacement.
Still another problem relating to the light box bulbs is the problem of replacing the bulb itself. For the light boxes to function optimally, it is crucial for the bulb to be correctly placed in the bulb holder to ensure proper alignment of the bulb on the optimum light path. Existing light boxes often have complicated assemblies which often require sending the light box to the manufacturer to ensure proper bulb alignment after bulb replacement.
In addition to above problems, light boxes often have a number of problems pertaining to the light produced by the light bulb. One problem is the heat produced in the light train as the light beam is narrowed to the input diameter of the fiber optic illumination cable. If too much heat is retained near the bulb, the life of the bulb can be reduced. Moreover, if too much heat is passed to the fiber optic cable, the cable may be damaged. Similarly, heat must be properly dissipated to prevent the connector itself from being heated to a point where physical handling becomes dangerous. Infrared and ultraviolet light components of the light produced by the bulb can damage both the tissue of the patient and the optical cable. For this reason, it is beneficial to prevent a portion of the infrared and ultraviolet wavelength components from reaching the fiber optic cable or the tissue. In light of the above, it is an object of the present invention to provide a light source incorporating a fiber optic cable connector which is uncomplicated. It is another object of the present invention to provide a light box including a connector which allows the fiber optic cable to be rotated relative to the light box. It is still another object of the present invention to provide a light box including a fiber optic cable connector which allows easy disconnection of the fiber optic cable from the light box while preventing accidental disconnection. Yet another object of the present invention is to provide a light box using a disposable bulb holder wherein the bulb can be correctly aligned by simple insertion of the holder into the light box. And yet another object of the present invention is to provide a light box using a bulb holder which automatically resets the hour meter of the light box during bulb replacement. Still further, it is an object of the present invention to provide a light box which maximizes heat dissipation and filters out undesirable light components prior to the produced light beam contacting the fiber optic cable. And further, it is an object of the present invention to provide a light source producing light having maximum intensity. Another object of the present invention is to provide a light box which is relatively easy to manufacture and which is comparatively economical.